There's been a flurry of news lately about "pit bull attacks," which has inspired a rash of ban proposals around the country. Your average uninformed person thinks, "Yeah, pit bulls are bad, obviously, because they are biting people. Let's ban them." So, let's have a bit of education.
First of all, "pit bull" is not an actual breed of dog, but refers commonly to several types of dogs: American Pit Bull Terrier (APBT), Staffordshire Bull Terrier, American Staffordshire Terrier, and Bull Terrier.
No dog has a "locking jaw." That would require some sort of skeletal or other type of modification, which simply doesn't exist. Also, if they had that, it would be enough to make them not be a "dog" anymore. That's a total myth.
All different breeds called "pit bulls" were mixes of terriers and bull dogs. Bull dogs used to be used for bull-baiting, which was a brutal sport that was outlawed in the 1800s. Then people started mixing the bull dogs with terriers to make them quick, and bred them to be dogfighters. Here is a KEY POINT: pit bulls were bred to be aggressive to other DOGS, not to HUMANS. The nature of a pit fight was such that there were usually 3 humans in the pit--both the dogs would have a handler, and there was also a referee/judge. These people didn't want to get bit, so the dogs were bred to have strong bite inhibition towards people. Moreso, these dogs lived generally as family members when they weren't fighting. (You have to remember that this was in the day before animal cruelty laws, so dog fighting was just a "sport" like dog racing or other things.) A dog that was human aggressive was not acceptable as a fighting dog, and was usually culled. Human aggression and dog aggression are two TOTALLY different traits. Other dogs are also animal aggressive, but nobody assumes that their aggression transfers over to people. Most hounds are to a degree small animal (i.e. rabbit or cat or fox) aggressive, most terriers are rat/squirrel aggressive, herding dogs are semi-aggressive to the animals they herd. Pit bulls were NEVER bred to be human aggressive, unlike "guarding dogs" such as mastiffs and others. Hopefully this point is clear: Dog aggression does not equal human aggression.
Pit bulls, specifically the APBT and the Am. Staff, were considered great family dogs throughout most of the 20th century--think Petey of Our Gang/Little Rascals. Helen Keller had a pit bull. A pit bull received medals for service in WWI. They were the all around family dog. They often do GREAT with kids because they have a high pain threshold, so they don't wince at every hug, poke, or other things kids might inflict uppon them. Both APBT and AmStaffs are descended from the Staff. Bull Terrier of England, which is called "the nanny dog" because it is SOOOOO good with kids.
Starting in the 1970s or so, pit bulls became the "cool" dog for unscrupulous people to get, because it portrayed a tough guy image. They are beautiful, muscular dogs, so it's easy to see why they were attracted to them. Dog fighting still goes on, but you can be assured that this is not the "gentleman's sport" that it was in the late 1800s. People now abuse their dogs to make them meaner, and they typically "bait" them with other dogs. The people who dogfight now are the bottowmdwellers of society, and don't care about dogs or people or anything else. Since pit bulls are still popular among "bad people" there are a LOT of "backyard breeders" who aren't doing the breed any services. The pit bulls you hear about on the news are the combination of bad breeding but mostly bad ownership.
I can sympathize with apprehensions about the breed, because until a year and a half ago I felt the same way. I was doing research on great danes, and looked at one dane owner's page, and she had the cutest dog. I asked her what it was, and she told me it was a pit bull. I was flabbergasted!! At that time, I only knew of Bull Terriers (the target dog) as pit bulls, and so I set out to learn about these dogs. I've read loads of books and information on line about them, so I consider myself a well educated amateur. I've met about 8-10 pit bulls in person, and they are wonderful dogs--they have great owners.
If you are interested in learning more, just for "education's sake" check out